Typically, Farraguts received additional 20mm mounts and in some instances additional 40mm. Trouble is, along with the Bensons, Gleaves, Sims and Porters, these DDs carried the brunt of the work until the Fletchers and Sumners came on line in sufficient numbers to relieve the constant operations. As a result, many weren't upgraded as heavily.
Let me know what ship you want to model in the 1941-42 timer period, and I'll give you specifics as to what you need to do to with regards to the ISW kit.
Jeff Herne
Modelwarships.com